A rule proposed by the U.S. Department of Labor that would set new standards for financial advisors serving retirement accounts could send $1 trillion in new assets to passive investment products, analysts at Morningstar Inc said Friday.

The report said such a rule would have broad impacts on brokerage firms, index companies and asset managers if more money moved into digital investment platforms and by changing behavior by financial advisers.

That could be a boon for firms such as BlackRock, which manages index-based ETFs through its iShares brand, ETF provider State Street Corp. and MSCI, which builds indexes. But such a rule could have a "mixed effect" on other asset managers and distributors of financial products, Morningstar said.